Acts of Betrayal
by Horror Movie Fan001
Summary: Title is probably self-explanatory. Rated for reasons. Requested by KiaraXKionFan
1. Chapter 1

_**Hello everyone, Horror here with another story requested by KiaraXKionFan. Before I start, I have to give my usual warnings. This story is rated for lemons/limes, language, same sex relations and slight character bashing, not as much as my other stories, just mild bashings.**_

 _ **Now enjoy the first chapter…though it will be short.**_

Isabella and Phineas happily walked down the street, hand-in-hand, as a gentle summer breeze blew past them. Isabella's phone went off as the two stopped and Isabella reached in her pocket and pulled her phone out before reading the text she just received and a small smile formed across her lips. She looked up at her confused boyfriend and gave a small smile, "I'm sorry Phineas, but I need to get to the clubhouse," Phineas arched a brow and Isabella sighed and shook her head, "We have some new girls and their initiation is today,"

"Oh…okay, I guess I'll walk-"

"No," Phineas jumped and looked at her in confusion, "No...initiations are secret, no one outside of the Fireside Girls have ever witnessed one...it's a rule, you understand,"

"Um...yeah, I guess so," Isabella smiled and nodded before kissing his cheek before she turned and began walking away.

Phineas took a deep breath and shook his head, "Okay...Isabella is at a meeting...so now what do I-" before he could finish, he heard rustling in a nearby bush.

Separating the bush, he saw a familiar mess of blonde hair kneeling behind the brush, "Katie?" Katie Parker looked up and faintly smiled before she slowly stood up, "What the hell are you doing here? Shouldn't you be getting to the clubhouse for that initiation thing or something?"

Katie frowned and took a deep breath, "Phineas, we're friends, right?"

"Um...yeah? You girls always help me and Ferb with our projects and-"

"And Isabella is your _girlfriend_ , right?"

Phineas slightly narrowed his eyes and shook his head, "Katie, I don't like the way you said that." Katie's frown deepened and Phineas took a deep breath, "You know we've been together since January. I took her to the winter formal, we go on dates, hang out more than usual and-"

"Okay, I get it, but...Phineas, why do you think I'm here if there is a Fireside Girl meeting?" Phineas arched a brow and scratched the side of his head in confusion, "Don't you find it a little funny? If there is a supposed initiation then all of us would be heading towards the clubhouse, not just Isabella."

"Um…so…what you're saying is…you quit the Fireside Girls?" Katie sighed and shook her head, "Um…initiation only involves your leader and second in-command? No…that doesn't make sense…Gretchen went to a family reunion yester-"

"Even if that was true, which it's not, then the next one under Gretchen will step in, which is me," Phineas continued to stare at Katie in confusion and Katie grunted, "Phineas, I know you've been oblivious to Isabella's feelings when we were younger, but you can't tell me that you're this dim. You've built an entire roller coaster, twice, you've fixed a time machine, you've designed a mini-golf course and you're telling me that you can't see what the hell is going on in front of you?"

"Um...you're jealous of our relationship?" Katie felt a slight pang in her chest as she looked down and slowly shook her head, "Then what seems to be the problem? Both Isabella and I are happy, everyone's happy for us, so what's-"

"You know Phineas, sometimes I don't think you're oblivious, but blind," Katie stepped out from behind the bush and turned her back towards Phineas. She looked back with narrowed his and spat, "But you're smart, you'll figure it out. And if you need a little more help, maybe you can talk to Ferb. I'm sure he'll be very helpful," Phineas tilted his head to the side as Katie scuffed, shook her head and began walking away.

Phineas rubbed the back of his head and shrugged his shoulders, "And...and what am I supposed to ask Ferb!" his question went ignored as Katie continued to walk away. Phineas sighed, shook his head and shoved his hands in his pocket before he turned and walked in the opposite direction from Katie.

 _ **Okay, the first chapter is short, but the story will develop as it goes on. Please enjoy everyone and please let me know what everyone thinks.**_


	2. Chapter 2

_**DavidC20OfficialWriter: I think you are referring to my other story Broken. Unless I am mistaken, my friend.**_

 _ **Enjoy the second chapter.**_

Phineas paced his and Ferb's room, a confused look crossing his face while Ferb sat in front of the computer, tapping on the keyboard. Groaning, Phineas fell back onto bed and stared up at the ceiling, "Are you done running a hole in our floor?" Ferb joked and Phineas groaned again, "What's the problem? The last time you were like this, it was because we couldn't do one of our projects, and we didn't have any paper…but then again, you nearly went-"

"Ferb, I need you to be honest here, am I blind?" Ferb arched a brow as Phineas sighed and sat up and shook his head, "I mean, I knew I was oblivious when it came to Isabella's feelings and everything, but we got together a few months ago and-"

"Is this going anywhere?" Ferb questioned, "Are you two having problems? Because I believe Candace will be better suited with this than I am, but-"

"Isabella and I were walking around when she got a text and she said she had a Fireside Girl meeting. I offered to walk her to the clubhouse, but then she got all defensive, saying there was an initiation and no outsiders have witnessed it, she kissed my cheek and left.

I soon found Katie hiding in the bushes and she and I talked and she claimed that there was no meeting and then she started acting strange before she angrily walked away and told me to talk to you…so…I'll ask again. Am I blind?"

Ferb sighed and leaned back on the chair, putting his hands behind his head, "You're my brother, and I'm going to be as honest as possible. You're not blind, not entirely," Phineas looked up and arched a brow, "Katie is jealous because she has a crush on you too,"

"Um…okay, but…that doesn't explain why she would lie about Isabella and the meeting, it's just petty-"

"Isabella isn't as faithful as you think. She's been seeing another guy behind your back for the past month and a half," Phineas stared at the green-haired teen in disbelief, "The other Fireside Girls, Buford and I found out. She threatened to kick the girls out of the troop and practice her judo on me and Buford if we spoke a word to you."

"And it took you this long to tell me? I thought we were best friends? What the hell, Ferb? We're supposed to be-"

"We are brothers, but you have to understand my predicament. Isabella just received her black belt and-"

Phineas sighed and shook his head, "I…I guess I can understand." He stood up and walked towards the door, "I'm…I'm going for a walk to try and clear my head," Ferb frowned as he watched his stepbrother walk out of the room.

Phineas walked down the street, his head down. Taking a deep breath, he looked and narrowed his eyes at the sight of the Fireside Girls clubhouse before quietly running towards it.

Leaning up against the side of the clubhouse, Phineas peered inside and his eyes widened when he spotted Isabella sitting on one of the benches, another guy sitting next to her, her arms wrapped around his neck and the guy's arms wrapped around Isabella's waist, their lips touching. Phineas sighed and shook his head before he turned and walked away from the clubhouse.

Phineas walked towards a house before knocking on the door. The door soon opened and an annoyed Katie stood in front of him, "Oh, it's you," Phineas looked at her, a painful look crossing his face, "What do you want?"

"I…I talked to Ferb, and he told me…everything," Katie crossed her arms, narrowed her eyes and leaned against the doorframe, "How Isabella was seeing someone behind my back, that she threatened you girls, him and Buford if you guys said anything to me,"

"So? What do you want me to do?"

"A little help?" Katie arched a brow and Phineas sighed and shook his head, "I…I saw Isabella and whoever that guy is at the Fireside Girls clubhouse and I…I need a little help. I can't go to my family, that'll only start a war, so I figured I'd ask you for some support,"

Katie continued to glare at him with narrowed eyes before Phineas looked down and a frowned formed across Katie's lips, "You know…no one deserves to be treated that way. Isabella had no right to cheat on you like that," she wrapped her arms around his neck and hugged him, "Why don't you come inside and stay for a while?"

"I…I don't think that's a good idea," Phineas sighed and shook his head, "You seem like you're still mad at me, and I wouldn't want to be a bother,"

"Just get in here," Katie gave a said smile before breaking from the one-sided hug and took Phineas by the hand and led him into the house.

 _ **Okay, so a mild update here. Please enjoy everyone and please let me know what everyone thinks.**_


	3. Chapter 3

_**DavidC20OfficialWriter: Yes, yes she will.**_

 _ **Enjoy the third chapter.**_

The two teenagers sat in the living room of the Parker house, Katie looked at Phineas as Phineas cupped a hand over his eyes and shook his head. Katie frowned and inhaled slowly, "So…are you okay, Phineas? I mean…I know we had an argument earlier…but…I…like I said, no one deserves that and-"

"Katie…did…did she like change her hair and I didn't say anything? I know I didn't miss her birthday, and we've only been dating for a few months, so I doubt I've forgotten our anniversary and-"

"Phineas," Phineas looked up and Katie frowned as she shook her head, "You…you didn't do anything wrong. Yes, you ignored her since we were like nine, but…like you said, you two recently got together. Something that Isabella wanted for years and…she…I don't know what to say without angering you because-"

"Katie, at this point, there's nothing you can say that'll piss me off," Katie stared at him with wide eyes and Phineas frowned, "I'm sorry, I know you can't stand it when people swear," Katie frowned and scooted closer to the redheaded genius, "I just…I thought we were happy. We went to the winter formal together, we went on a few dates, I even invented a few things specifically for her and…why?"

Katie held Phineas hand and Phineas sighed, "I don't know…maybe…maybe I should confront her about this and see where she stands on-"

"You don't want to do that, Phineas," Phineas looked at the blonde in confusion, "I know you're hurting, I know you're angry, but going to Isabella and telling her you know about this will only end badly. Isabella will counter it with the times you had to leave dates early and she'll think-"

"But I've never cheated on her. Yeah, I had to leave a few dates earlier than expected, but that was because mom broke her leg and mom and dad needed me, Ferb and they even called Candace to come home and help out for a few weeks while mom was recovering.

Another time I left a date early was…well I wasn't feeling well…I had the flu, she even told me that we could reschedule the date," Katie frowned and Phineas looked at her in confusion, "What? Did I do something wrong?"

"Phineas…the day you were sick with the flu…I think that's the day Isabella started dating that guy…I could be wrong, I'm not trying to start anything, but…I believe it was the day she started seeing that other guy."

Phineas sighed and shook his head, "Katie, if you're trying to make me feel better, it's not working," Katie took a deep breath and Phineas frowned, "I'm sorry. I came to you for comfort and I'm acting like the biggest jerk in the world right now."

"Well…you just leaned your girlfriend has been cheating on you for months now." Phineas sighed and Katie held his hand, "And…maybe I wasn't in the best of moods when I wanted to tell you earlier…I just…I couldn't stand that you were being led on like that…it wasn't right,"

"Yeah…I guess so," Phineas frowned and looked at the blonde teen, "Katie…Ferb also told me something else…I found it a little strange…and confusing." Katie arched a brow and Phineas shook his head, "He said you were jealous because you have a crush on me. I need to know…is that-"

"Phineas, we're here to help you, not ask me questions,"

"No…Katie, were you jealous of mine and Isabella's relationship because you have a crush on me as well?" Katie frowned and looked down slowly, "Katie…I'm just asking because-"

"I…I…look Phineas, I don't think now is the time and place to talk about it." She unknowingly leaned up again him, resting her head on his shoulder.

 _ **Small chapter, I know. Please enjoy everyone and please let me know what everyone thinks.**_


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